1. Field of Invention
This invention relates to a hybrid drive system incorporated in a vehicle and a vehicle equipped with the hybrid drive system, and more specifically, to an output structure from a drive (assist) electric motor.
2. Description of Related Art
Conventionally, a hybrid drive system of a so-called mechanical distributing type (a distribution type or a two motor type) has been provided in a vehicle (registered trademark name “PRIUS”) for commercial practice, in which the engine output is distributed in a planetary gear to a control motor and to a traction output side, and the motor is controlled mainly as a generator for step-less control of the output torque of the planetary gear, and torque of another electrical motor for driving (assisting) is combined with the output torque of the planetary gear as required and then output to the output shaft.
The above hybrid drive system of mechanical distributing type includes a hybrid drive system for FF (front engine, front drive) as disclosed in, for example, Japanese Patent Laid-Open Publication No. Hei 8-183347. An FR-type hybrid drive system is also possible. An example of the FR-type hybrid drive system is shown in FIG. 9.
In a vehicle 1 equipped with the hybrid drive system, as shown in FIG. 9, an internal combustion engine 5, such as a gasoline engine or the like is provided. The longitudinal direction of the engine 5 is aligned with the crank shaft and the engine 5 is, in a portion generally between the front wheels 3, 3, in a front part of a vehicle body 2. Further, the above two-motor type hybrid drive system 6 is arranged adjacent to and behind the engine 5. The hybrid drive system 6 is generally aligned with the crank shaft in the axial direction and has a first motor (electric motor for control) 7, a power distribution planetary gear 9, and a second motor (electric motor for drive) 10 arranged in order from the engine side.
The above hybrid drive system 6 has an input shaft 12 connected via a damper 8 with an output shaft 5a which is provided with the rear protruding portion of the engine crank shaft. The first motor 7 is arranged coaxially with the input shaft 12 on the outer radial side of the input shaft. The first motor 7 is provided with an AC permanent magnet synchronous type (brushless DC motor), and has a stator 13 fixed on the case, and a rotor 15 which is rotatably supported on the inner radial side of the stator with a predetermined air gap being provided therebetween.
The above power distribution planetary gear 9 is provided with a simple planetary gear arranged coaxially with the input shaft 12, and has a carrier CR1 connected with the input shaft 12 and supporting a plurality of planetary pinions P1, a sun gear S1 connected with the rotor 15, and a ring gear R1 which serves as a traction output portion. The ring gear R1 is connected with an output shaft 16 extending backward on the same axis line as the input shaft 12.
The second motor 10 is provided with a similar brushless DC motor larger than the motor 7. The second motor 10 is arranged coaxially with and on the outer radial side of the output shaft 16, and has a stator 17 fixed to the case, and a rotor 19 rotatably supported on the inner radial side of the stator 17 with a predetermined air gap being provided therebetween.
The output shaft 16 protrudes from the case and further extends toward the rear of the vehicle where it is connected with a differential device 22 via a flexible connection 20 and a known propeller shaft 21 (actually, a universal joint, center bearing and the like are provided though they are omitted in the figure). Further, the rotation (drive) is transmitted from the differential device via the left and right drive shafts 23l, 23r to the rear wheels 25, 25.
In the FR-type vehicle 1 equipped with the hybrid drive system 6, the output of the engine 5 is transmitted to the carrier CR1 of the power distribution planetary gear 9 via the damper 8 and the input shaft 12. In the planetary gear 9, the above engine output is distributed and transmitted from the sun gear S1 to the first motor (motor for control) 7, and from the ring gear R1 to the shaft 16 for traction. At this point, the first motor 7 is controlled for step-less adjustment of the output torque and rotation which is input to the output axis 16, and then output therefrom. Furthermore, in a case where a large torque is required at a time of starting or other cases, the second motor (motor for drive) 10 is driven, then the motor torque of the second motor 10 assists the torque of the output shaft 16 and is transmitted to the propeller shaft 21. The motor torque is then further transmitted to the rear wheels 25 via the differential device 22 and the left and right drive shafts 23l, 23r. 
Note that the second motor 10 uses electrical energy generated by the first motor 7, and, additionally, when the generated energy is insufficient for the required energy, it uses battery energy generated by the first motor 7 when functioning as a generator and stored in the battery. Furthermore, the second motor 10 functions as a regenerative generator when braking is applied.